Signet ring cell adenocarcinoma of the urachus is an extremely rare variety of adenocarcinoma of the urachus; only 23 cases have been reported in the literature to date. In the present report we discuss two more cases of this type and review the literature. For our first case, a 17-year-old man was treated with partial cystectomy with en-bloc excision of the urachus and umbilicus. He received local radiotherapy because of positive surgical margins. Local recurrence occurred after 21 months of diagnosis and he was lost to follow up. For our second case, a 31-year-old man was found to have peritoneal carcinomatosis at the time of surgery and partial cystectomy was carried out as a palliative procedure for hematuria. He received six cycles of chemotherapy, a combination of methotrexate, vinblastine, adriamycin and cisplatinum. The patient's response to the chemotherapy lasted for 8 months, after which his disease progressed and he died 19 months after diagnosis.